ABSTRACT
Resumen Evaluar la influencia del tipo de terminación marginal; filo de cuchillo (F) y chamfer (C) sobre la resistencia flexural de coronas de disilicato de litio CAD/CAM en espesores de 0,8 mm y 0,5 mm. Materiales y métodos: 40 premolares superiores sanos, en 2 grupos de acuerdo con el tipo de terminación G1=F y G2=C; 2 subgrupos referentes al espesor del material Sg1=0,8mm y Sg2 0,5 mm (5 coronas por cada subgrupo), se sometieron a fuerzas de compresión vertical (v) y horizontal (h). Se observó el tipo de fractura más frecuente; cohesivas en porcelana (cp), adhesiva en porcelana (ap), mixta pequeña (mp) y mixta larga (ml). Resultados: En preparaciones a 0,8 mm y 0,5 mm, existió diferencia significativa en relación con la mejor terminación, esta fue el C; sus valores fueron, Sg1 (h=1347,2 N / v=1402,0. F; Sg1 (h=965,6 N/ v= 794,8 N). F a 0,5 mm mostró mejor desempeño ante fuerzas horizontales. C; Sg2 (h=924,8 N /v=813,4 N) y para F; Sg2 (h=1217,0 N /v= 576,0 N). Conclusiones: Tipo de fractura más frecuente es cp y ap. Terminación chamfer y filo de cuchillo pueden ser utilizados con seguridad, pues muestran valores aceptables de resistencia flexural, al reducirse el grosor de la restauración en chamfer reduce su resistencia, el filo de cuchillo la aumenta.
Abstract Objective: To evaluate the influence of the type of shoulder margins; Knife edge (F) and Chamfer (C) on the flexural strength of CAD / CAM lithium disilicate crowns in thicknesses of 0.8 mm and 0.5 mm. Materials and Methods: 40 healthy upper premolars, in 2 groups according to the type of termination G1 = F and G2 = C; 2 subgroups referring to the material thickness Sg1 = 0.8mm and Sg2 0.5mm (5 crowns for each subgroup), were subjected to vertical (v) and horizontal (h) compression forces. The most frequent type of fracture was observed; cohesive in porcelain (cp), adhesive in porcelain (ap), mixed small (mp) and mixed long (ml). Results: In preparations with 0.8 mm and 0.5 mm thicknesses, there was a significant difference in relation to the best termination, this was C; their values were Sg1 (h = 1347.2 N / v = 1402.0.F; Sg1 (h = 965.6 N / v = 794.8 N) .F at 0.5 mm showed better performance against horizontal forces C; Sg2 (h = 924.8 N / v = 813.4 N) and for F; Sg2 (h = 1217.0 N / v = 576.0 N) Conclusions: The most frequent type of fracture is cp and ap finishing chamfer and knife edge can be used safely show acceptable values of flexural strength, by reducing the thickness of the chamfer restoration reduces its strength, the knife edge increases it.
Subject(s)
Crowns , Dental Materials/analysisABSTRACT
The marginal adaptation of cast metal crowns is essential for the success of cast restoration. The marginal design, die spacer and the seating force are considered as important factors effecting the marginal fit of cast metal crowns. Aims and Objectives; The aim and objectives of the present study is to evaluate the marginal fit of cast metal crowns 1.With three different marginal designs that are shoulder, shoulder with bevel and chamfer 2.With and without die spacer 3.Under seating forces 100N and 300N. METHODOLOGY: The study was done using 3 brass dies of 6mm height 10o taper with three different marginal designs shoulder, shoulder with 45o bevel and chamfer . 20 impressions of each metal die were made and casts were poured. 10 specimens of each group were coated with die spacer while the other 10 specimens were to serve as control group. Cementation done with GIC under two different seating forces (100N and 300N). The marginal discrepancy is determined by measuring the crown height before and after cementation. From this study it was concluded that specimen with combination of chamfer marginal design with die spacer under 300N seating force exhibited superior marginal adaptation.
ABSTRACT
Este estudo avaliou a influência da confecção da canaleta e posterior restauração com resina composta, na resistência de união da colagem de fragmento dental. Quarenta incisivos bovinos foram fraturados a 3 mm da junção cemento-esmalte e divididos em 4 grupos (n=10) nos quais a colagem do fragmento foi realizada com cimento resinoso dual após hibridização das superfícies de adesão. No grupo 1, foi feita somente a colagem, sem preparo adicional. Nos outros grupos as canaletas (0.7mm de profundidade)foram feitas e restauradas sobre a linha de união com diferentes localizações. Grupo 2, canaleta na facevestibular; grupo 3, canaleta na face lingual; grupo 4, canaleta nas faces vestibular e lingual. As amostras foram testadas usando dispositivo em forma de faca em máquina de ensaio mecânico(0.5mm/min) num ângulo de 90 na face lingual. Os valores em Kgf foram submetidos à análise estatística (?=0.05) e o teste de Kruskall-Wallis não mostrou diferença significativa entre os grupos (p=0.565)...
The effect of the chamfer and posterior restoration using composite resin on the bond strength of dental reattachment was evaluated. Forty bovine teeth were fractured 3 mm above the cement-enamel junction, divided in 4 groups (n=10) and the fragments were reattached with a dual resin cement afterhybridization of the bonding surfaces. In the group 1 the reattachment was done without additional preparation but in the other groups chamfers (0.7 mm depth) were made and restored with composite resin along the bond line in different locations. Group 2, chamfer on the buccal aspect; group 3, chamferon the lingual aspect; group 4, chamfer on both buccal and lingual aspects. Specimens were sheared using a spade blade in a test machine (0.5 mm/min) at 90° to the lingual surface. The data (Kgf) were submitted to statistical analysis (?=0.05) and the Kruskall-Wallis test showed no significant differences among the groups (p=0.565)...